This invention relates to a post frame machine for applying a pulling force to a workpiece such as a portion of a damaged automobile to be restored to an original configuration. More particularly, it relates to such a post frame machine which can be used to apply not only a pulling force to such a workpiece, but can be used to apply two independent pulling forces which may be the same or different to such a workpiece. More particularly still, these two pulling forces can be applied to two closely spaced-apart portions of the workpiece.
Post frame machines are generally known in the prior art and are used extensively in the autobody business to repair damaged automobile bodies. For example, prior post frame machines are shown in U.S. Pats. Nos. 3,566,667; 3,589,680; 3,612,482 and 3,754,432. None of these prior post frame machines have the capability of applying simultaneously dual pulling forces to a workpiece. In the past, whenever it was desired to apply two pulling forces simultaneously to a workpiece, it was necessary to utilize two such post frame machines. Using two post frame machines, however, is sometimes difficult to do since the machines are bulky and awkward to use. Also, both machines must be tied down. if the pulling forces are to applied to two closely spaced-apart portions of a workpiece, the difficulties are compounded because of the bulkiness and awkwardness of the post frame machines and the need to anchor them down. The post frame machine of the present invention overcomes the difficulties of both applying simultaneously dual pulling forrces to a workpiece, and particularly when the dual pulling forces are to be applied to two closely spaced-apart portions of a workpiece.
Another disadvantage and safety hazard associated with the prior post frame machines is that the load chain which applies the pulling force to the workpiece is sometimes released from tension and is inadvertently released such that it snakes or whips. In doing so, a worker may be struck and injured by the load chain. With the post frame machine of the present invention, this safety hazard is virtually eliminated.
The post frame machine of the present invention generally is formed of two vertical support posts which are fixedly mounted with a base frame in closely spaced relationshp and which include therein respectively a telescopically movable power post having a chain sprocket on the upper end thereof for applying a pulling force to a load chain as the power post is extended. A fulcrum pulley is carred by each of the support posts and can be vertically adjusted and positioned along the length of the support post. The support posts are spaced apart sufficiently to permit the fulcrum pulleys to be independently vertically adjusted without interfering with one another. The power posts are extended and retracted by hydraulic cylinders which are disposed at the lower ends of the support posts and coupled to the lower ends of the power posts. The load chains which apply the pulling force to a workpiece extend about sprocket wheels carried by the fulcrum pulleys and about the sprocket wheels carried by the power posts, and the free ends thereof are secured locked into position by chain locks affixed to the support posts. The fulcrum pulleys also include chain locks for locking the load chains under tension when the power posts are retracted so that the free ends of the load chains are prevented from snaking or whipping.